Impact of ITPA gene polymorphism for predicting anemia and treatment outcome in HCV infected patients taking Sofosbuvir Ribavirin therapy

Abstract

Background: Globally, 80 million people are suffering from chronic Hepatitis C virus (HCV) infection. Sofosbuvir ribavirin-based anti-HCV therapy is associated with anemia and other adverse effects. Polymorphisms of Inosine triphosphatase (ITPA) gene may cause functional impairment in the Inosine triphosphate pyrophosphatase enzyme, resulting in enhanced sustained viral response (SVR) and protection from ribavirin-associated anemia in patients on therapy. The study objective was to investigate the effect of Inosine triphosphatase gene polymorphism on SVR achievement, hemoglobin decline and ribavirin dose reduction in patients on therapy.

Methods: This prospective cohort study was of 170 hepatitis C infected patients received 6-month sofosbuvir ribavirin therapy. Patient viral load, reduction in ribavirin amount, liver function test, and complete blood count were noted monthly. Inosine triphosphatase variants rs1127354 and rs7270101 were assessed through the restriction fragment length polymorphism and confirmed using Sanger sequencing. The impact of polymorphism on cumulative reduction of ribavirin, and anti-HCV therapy outcome were studied.

Results: A total of 74.3% of patients had ITPA rs1127354 CC genotype, 25.7% were CA and AA 0%. The frequency of ITPA genotype rs7270101-AA was 95%, AC 5%, and CC was 0%. ITPA rs1127354-CA had a notably positive impact on SVR achievement with a zero-relapse rate. ITPA rs1127354-CA genotype was significantly (P ˂0.05) protective against ≥ 2 g/dl Hb reduction from baseline to 1st, 2nd and 6th months of therapy. During treatment, Hb reduction ≥ 10 g/dl was frequently observed in rs1127354-CC genotype and rs7270101-AA genotype patients. Ribavirin dose reduction was significantly (P ˂0.05) high in rs1127354-CC genotype as compared to genotype CA whereas no significant difference was observed in ribavirin dose reduction in rs7270101 AA and non-AA genotype. Patient baseline characteristics such as age, body mass index, rs1127354-CC genotype, and baseline Hb were significantly associated with significant Hb reduction.

Conclusion: Pretreatment evaluation of ITPA polymorphism can be a diagnostic tool to find out patients at risk of anemia and improve treatment adherence. ITPA genotype rs1127354-CA contributes to improved compliance with ribavirin dose and protects against hemoglobin decline in HCV patients while taking ribavirin-based therapy. However, ITPA rs1127354, rs7270101 polymorphism have no significant impact on SVR achievement.

Keywords: Anemia; HCV; ITPA; Polymorphism; Ribavirin.

Fig. 1

Sequencing chromatogram of ITPA polymorphism rs1127354 and rs7170101. (A) Chromatogram of rs1127354-CC genotype. (B) Chromatogram of rs1127354-CA genotype (Missense mutation). Arrow indicates the point where the mutation occurred. (C): Chromatogram of rs7270101-AA genotype. (D) Chromatogram of rs7070101-AC genotype (Splice variant). Arrow indicates the point where the mutation occurred, A, T, G, and C present nucleotide positions as adenine, guanine, cytosine, and thiamine

Fig. 2

ITPA rs1127354, rs7270101 genotype wise presentation of SVR achievers and relapsed HCV patients receiving Sofosbuvir ribavirin. Sustained Viral response (SVR)

Fig. 3

Hb reduction ≥ 2 g/dl from baseline to 1st month according to ITPA polymorphism. The height of bars presents the number of HCV infected patients with belong to each ITPA genotype experience hemoglobin reduction after weight-based ribavirin (for ˂75Kg weight 100 mg/day and > 75Kg body weight 1200 mg/day) was given

Fig. 4

Month wise ≥ 2 g/dl Hb reduction with reference of ITPA rs11273547 CC and CA genotype. Months are presented as M1, M2, M3, M4, M5, M6. The bars present percentage of patients with each ITPA genotype experience hemoglobin reduction. Significantly high number of patients with ITPA SNP rs1127354-CC experience ≥ 2 g/dl Hb reduction at months M1, M2, and M4 mentioned by P value

Fig. 5

Changes in mean hemoglobin concentration of HCV infected patients during Sofosbuvir and Ribavirin treatment. (A) Changes in mean Hb concentration of overall patients. (B) Changes in mean Hb concentration with reference of ITPA rs1127354 CC and CA. Base line (BL), Month of treatment (M1, M2, M3, M4, M5, M6)

Fig. 6

Ribavirin dose reduction relative to ITPA polymorphism in HCV patients taking Sofosbuvir ribavirin therapy. The bars present number of patients experience ribavirin dose reduction by ITPA polymorphism rs1127354 CC and CA genotype and ITPA rs7270101 AA and Ac genotype

Fig. 7

Ribavirin dose reduction on basis of ITPA genotype (Kaplan-mere curve). (A) Ribavirin reduction in rs1127354-CC & CA genotype. (B) Ribavirin dose reduction in ITPA rs7270101 AA and AC genotype